A method includes etching a semiconductor substrate to form trenches, with a portion of the semiconductor substrate between the trenches being a semiconductor strip, and depositing a dielectric dose film on sidewalls of the semiconductor strip. The dielectric dose film is doped with a dopant of n-type or p-type. The remaining portions of the trenches are filled with a dielectric material. A planarization is performed on the dielectric material. Remaining portions of the dielectric dose film and the dielectric material form Shallow Trench Isolation (STI) regions. A thermal treatment is performed to diffuse the dopant in the dielectric dose film into the semiconductor strip.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A device comprising: a semiconductor substrate; an isolation region extending into the semiconductor substrate, wherein the isolation region comprises: a dielectric liner; a first dose film comprising a portion overlying a first bottom portion of the dielectric liner, wherein the first dose film comprises a first dopant of a first conductivity type selected from p-type and n-type; and a dielectric region over a second bottom portion of the first dose film; a semiconductor fin protruding higher than top surfaces of the isolation region; and a gate stack extending on a top surface and sidewalls of the semiconductor fin.
2. The device of claim 1 , wherein the first dose film comprises sidewall portions connecting to opposing ends of the second bottom portion of the first dose film.
3. The device of claim 1 , wherein the first dopant has a highest doping concentration in the first dose film, and doping concentrations of the first dopant in the dielectric liner and the dielectric region are lower than the highest doping concentration.
4. The device of claim 1 , wherein the first dose film comprises silicon oxide, with the first dopant being doped in the silicon oxide.
5. The device of claim 1 further comprising an anti-punch-through region in a portion of the semiconductor substrate, wherein the portion of the semiconductor substrate is on a side of, and contacting, the isolation region, and wherein the anti-punch-through region has a top end higher than the isolation region.
6. The device of claim 1 further comprising: a second dose film comprising an additional portion overlying the second bottom portion of the first dose film, wherein the second dose film comprises a second dopant of a second conductivity type opposite to the first conductivity type.
7. The device of claim 6 , wherein a first highest doping concentration of the first dopant is in the first dose film, and a second highest doping concentration of the second dopant is in the second dose film.
8. The device of claim 6 , wherein the second dose film is in physical contact with the first dose film.
9. A device comprising: a semiconductor substrate comprising a bulk portion and a semiconductor strip over the bulk portion; an isolation region over and contacting the bulk portion and the semiconductor strip, wherein the isolation region comprises: a first dose film comprising a first dopant of a first conductivity type; and a second dose film comprising a second dopant of a second conductivity type opposite to the first conductivity type, wherein each of the first dose film and the second dose film comprises a bottom portion and sidewall portions higher than and connecting to the bottom portion; and an anti-punch-through region in the semiconductor strip, wherein the anti-punch-through region is of the first conductivity type.
10. The device of claim 9 , wherein the anti-punch-through region comprises both of the first dopant and the second dopant.
11. The device of claim 9 , wherein the anti-punch-through region extends higher than a top surface of the isolation region.
12. The device of claim 9 , wherein the anti-punch-through region extends lower than a bottom surface of the isolation region.
13. The device of claim 9 further comprising: a semiconductor fin over and joined with the semiconductor strip; and a gate stack on a top surface and sidewalls of the semiconductor fin.
14. The device of claim 9 , wherein the semiconductor substrate further comprises an additional semiconductor strip over the bulk portion, and the device further comprises: an additional isolation region over and contacting the bulk portion and the additional semiconductor strip, wherein the additional isolation region comprises a third dose film comprising the second dopant; and an additional anti-punch-through region in the additional semiconductor strip, wherein the additional anti-punch-through region is of the second conductivity type.
15. The device of claim 14 further comprising a dielectric material comprising: a first portion over and contacting the second dose film; and a second portion over and contacting the third dose film.
16. A device comprising: a semiconductor substrate; and an isolation region extending into the semiconductor substrate, wherein the isolation region comprises: a dielectric liner having a first bottom portion and first sidewall portions contacting a top surface and sidewalls of the semiconductor substrate; and a first dielectric dose film separated from the semiconductor substrate by the dielectric liner, wherein the first dielectric dose film comprises a second bottom portion and second sidewall portions; and a dielectric region separated from the dielectric liner by the first dielectric dose film, wherein the first dielectric dose film, the dielectric liner, and the semiconductor substrate are doped with a first dopant of a first conductivity type, and the first dopant has a first highest doping concentration in the first dielectric dose film.
17. The device of claim 16 , wherein concentrations of the first dopant decrease in a first direction from the first dielectric dose film to the dielectric liner, and in a second direction from the first dielectric dose film to the dielectric region.
18. The device of claim 16 , wherein a portion of the semiconductor substrate adjacent to the isolation region comprises the first dopant.
19. The device of claim 16 further comprising a second dielectric dose film between the first dielectric dose film and the dielectric region, wherein the second dielectric dose film is doped with a second dopant of a second conductivity type opposite to the first conductivity type.
20. The device of claim 19 , wherein the second dopant has a second highest doping concentration in the second dielectric dose film.
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December 26, 2019
July 21, 2020
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